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BQ24630: Please review the schematic for charging-only function

Chase Jeong
Genius 5470 points
Part Number: BQ24630

Hi E2E Team,

my customer wants to use BQ24630 IC for only charging the battery, not for the adapter power to system.

In this reference design, we have 3 questions.

1. we will not use "SYSTEM" net on the top-right of the design. is it okay to remove Q3, C15, R15, and R19? How about Q4? can we remove it too?

2. Can we remove Q1 FET? (we will remain R18 1Kohm resistor for pullup with adaptor voltage)

3. what is the meaning of R20 2ohm?

and, here is the modified design;

Please review this schematic, and let me know if there are any points for improvement. Thanks.

Best regards,

Chase

  • 0
    TI__Mastermind 24075 points

    Hi Chase,

    1.  Yes, this okay.
    2. Q2 is less important as it limits inrush current to the system by providing limited dI/dt when connecting the adapter to the system by controlling the FET turn-on time. If you want to remvoe the Q1 FET, as it also provides added input reverse blocking protection, it would be recommended to replace it with a diode atleast.
    3. R20 along with C16 make a damping RC network to damp input hot plug-in oscillation. As a result, the overvoltage spike is limited to a safe level.

  • 0 in reply to Kedar Manishankar
    Genius 5470 points

    Hi Kedar,

    Thank you for the reply.

    1-1. it will be okay to remain \BATDRV pin as floating?

    1-2. How about Q4? If we remove Q4, it will also remain HIDRV and PH pin as floating too. is it okay?

    2. if we use Q1 FET, we have to connect \ACDRV pin to the gate of Q1. and if we don't use Q1 FET, is it okay to remain \ACDRV pin as floating?

    Please check this issues. Thanks.

    Best regards,

    Chase

  • 0 in reply to Chase Jeong
    TI__Mastermind 24075 points

    Hi Chase,

    1.   Yes
    2. No. This is a buck charger so you need the switching FET.
    3. Yes, it is okay to leave ACDRV floating. However we still recommend using a diode for reverse voltage protection, if not using the input reverse blocking FETs